--- title: "Goals and design challenges of DS" subject: "Distributed System" chapter: 1 key: "semester_7/distributed_system:ds-goals-challenges" source: https://www.bctengineer.com/q/semester_7/distributed_system/ds-goals-challenges site: BCT Engineering --- # Goals and design challenges of DS Distributed System · Chapter 1: Introduction - Asked in: 2076 Asoj; 2074 Asoj, 2+6 marks; Model question (asked 3 times) - Video: [Issues And Goals Of Distributed System In Hindi](https://www.youtube.com/watch?v=adYq9jBcHsc) — Last moment tuitions - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/distributed_system/ds-goals-challenges - Whole chapter: https://www.bctengineer.com/md/semester_7/distributed_system/chapter-1 ## Question What are the major goals of a distributed system? What are the challenges during the design of a distributed system? ## Short answer Major goals are resource sharing, transparency, openness, scalability, and concurrency with fault tolerance. Design challenges include heterogeneity, openness, security, scalability, failure handling, concurrency, transparency, and quality-of-service/time issues such as lack of a global clock. ## Answer #### Goals of a distributed system A **distributed system** is a collection of independent computers, connected by a network and running distribution middleware, that appears to its users as a single coherent system. Its components communicate and coordinate their actions only by passing messages (Tanenbaum; Coulouris). - **Resource sharing:** users and programs share printers, files, data, storage and compute power across the network (for example the web, cloud storage). - **Transparency:** hide the fact that processes and resources are physically spread over many machines. - **Openness:** the system offers services through standard, published interfaces so that parts from different vendors can interoperate and be extended. - **Scalability:** the system keeps working well as users, resources and geographic spread grow. - **Concurrency and fault tolerance:** many users work at once, and the system keeps running when some component fails. #### Design challenges 1. **Heterogeneity:** different networks, hardware, operating systems, programming languages and data formats must work together. Middleware (CORBA, Java RMI) and standards hide the differences. 2. **Openness:** interfaces must be published, specified (for example by IDL) and extensible without breaking existing parts. 3. **Security:** confidentiality, integrity and availability must be protected over open networks. Encryption, authentication and access control are needed, and denial-of-service attacks are hard to stop. 4. **Scalability:** the design must avoid central bottlenecks (single server, central table, central algorithm). Techniques are replication, caching, partitioning and distribution of work. 5. **Failure handling:** components and links fail independently and partially. We need failure detection, masking (retransmission, replication), tolerance and recovery. 6. **Concurrency:** shared resources are accessed at the same time, so synchronisation and consistency control are needed. 7. **Transparency:** hiding distribution completely is costly and sometimes impossible (network latency, partitions). 8. **Quality of service and time:** timeliness and reliability must be guaranteed, and the lack of a global clock makes coordination difficult. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which description best fits a distributed system? A. A single powerful computer with many terminals B. Several computers sharing one memory and one clock C. Independent computers linked by a network that appear to users as one coherent system D. Any group of computers that never communicate Answer: C. A distributed system is a set of independent networked computers that present a single coherent system, coordinating only by message passing. (Key point: Definition) 2. What is the goal of transparency in a distributed system? A. To hide the fact that processes and resources are spread over many machines B. To publish all machine locations to users C. To make every component use the same hardware D. To remove the need for a network Answer: A. Transparency conceals the physical distribution so users see one system. (Key point: Transparency goal) 3. Which design approach avoids bottlenecks to achieve scalability? A. Using one central table for all names B. Placing all processing on one powerful server C. Using a single central algorithm for coordination D. Replication, caching, partitioning and distributing work instead of a single central server or table Answer: D. Central servers, tables and algorithms become bottlenecks; replication, caching and partitioning spread the load. (Key point: Scalability challenge) 4. Why is failure handling difficult in a distributed system? A. All components always fail together B. Components and links fail independently and partially, so failures must be detected, masked and recovered from C. Failures never happen over networks D. Failure of one node always stops the whole system Answer: B. Partial, independent failures require detection, masking (retransmission, replication), tolerance and recovery. (Key point: Failure handling) ## Related in Distributed System - [Goals, need of transparency, challenges](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Agoals-transparency-challenges) — Distributed System, chapter 1 - [Challenges of DS with example](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Ads-challenges-example) — Distributed System, chapter 1 - [DS as a single coherent system](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Asingle-coherent-system) — Distributed System, chapter 1, asked 2× - [Concurrency control goals and mechanisms](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Acc-goals-mechanisms) — Distributed System, chapter 8 - [Centralized vs distributed; design issues](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Acentralized-vs-distributed) — Distributed System, chapter 1 - [Autonomous vs distributed system](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Aautonomous-vs-distributed) — Distributed System, chapter 1 ## Related in other subjects - [Design goals and performance metrics](https://www.bctengineer.com/question.md?key=semester_5%2Fcomputer_organization_and_architecture%3Adesign-goals-metrics) — Computer Organization and Architecture, chapter 1 - [Design goals of digital modulation; coherent BPSK](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Adesign-goals-bpsk) — Communication Systems, chapter 7 - [Challenges of modeling a physical system](https://www.bctengineer.com/question.md?key=semester_6%2Fembedded_system%3Amodeling-physical-system-challenges) — Embedded System, chapter 7 - [Short note: Distributed system implementation](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Ashort-note-distributed-implementation-issues) — Object Oriented Analysis and Design, chapter 4